Firoloida desmarestia

Firoloida desmarestia Lesueur, 1817

Worldwide warm waters. Swimming predator on gelatinous zooplankton in the upper layers of the seas (epipelagic and mesopelagic, according to the daily vertical migration of the preys). Only the larva bears a shell, snail-shaped with only two whorls. There are many synonyms, due to the wide distribution of the species over the world: aculeata, gracilis, liguriae, vigilans… blainvilleana, gaimardi, lesueurii…

400m deep, off Alborán island. 0,6mm.

The species in C. A. Lesueur: “Characters of a new genus and descriptions of three new species upon which it is formed; discovered in the Atlantic ocean in the months of March and April, 1816; lat, 22'9”, Journal of the Academy of Natural Sciences of Philadelphia vol. I .I, Philadelphia 1817, plate II.

« Body long, glabrous, hyaline, acuminated at each extremity; no gelatinous points. Plate 2, fig. 1.b. position of the eyes and nervous ganglion between them; a. oviduct, magnified. Inhabits the ocean near Martinique, taken in March 1816. Dorsal fin rounded, nearer to the eyes than to the nucleus. Lenght of the body two inches. » – The genus is monospecific.

Other synonym: Cyclostrema solutum di Geronimo, 1974, based on minute shells found at 4210m deep, Ionian Sea.

« Recent bibliographical research (Richter 1968 and 1974; Van der Spoel 1976) led me to the conclusion that C. solutum cannot be considered a valid species, being actually the larval deciduous shell of the pelagic mollusc Firoloida desmaresti, Lesueur 1817 (Heteropoda: Pterotracheidae) of which it therefore becomes a synonym. » – I. Nofroni: “Cyclostrema solutum, di Geronimo 1974, larval shell of Firoloida desmaresti Lesueur, 1817 (Heteropoda: Pterotracheidae)”, La Conchiglia 186-187, Roma 1984, p.23.

Larva from 1m deep, uvala Stari Trogir, Sevid area, Split-Dalmatia Comitat, W. Croatia. Original picture provided by V. Cetinić-Koća (HR) – (CC BY-NC-SA).